Cain was so angry he would not be talked out of his sin—even by God.

Eve, however, had to be talked into her sin by Satan; but Cain “belonged to the evil one” (1 John 3:12).

It is as if he could not wait to destroy his brother—a natural man’s solution to his own failure. God’s advice was that if Cain would please God by doing what is right, all would be well. But, if not, sin would be crouching at his door, ready to overcome him. Sin desires to have Cain (these words show God’s interpretation of “desire,” the same Heb. word, in Gen. 3:16), but Cain could have the mastery over it. Here is the perpetual struggle between good and evil. Anyone filled with envy and strife is prey for the evil one.

- Bible Knowledge Commentary